Air handling units and controls for heating, ventilation and air conditioning (HVAC) are expensive and sensitive to outside contaminants. The outside contaminants can produce health problems, such as allergies and other illnesses (see EPA article, EPA-402-K-97-002, October 1997, “Should You Have Your Ducts Cleaned” at page 2), and can erode warranties on the HVAC system. To avoid health problems and maintain system warranties, it is imperative that contaminants such as dirt, dust, moisture and other debris are kept out of the HVAC system.
This is often a difficult task, as the HVAC systems are usually hung during building construction. The ductwork is hung after the building is framed, but not yet completed. The ductwork is usually hung long before the HVAC unit itself is installed. This delay results in a great need for temporary duct covers. HVAC units are commonly roof-mounted. The units mount on a curb that has a supply and a return opening. This curb is placed in a hole cut in the roof. The curb openings are shaped to fit the HVAC unit. Until the unit is fitted to the curb, the openings are left uncovered. To keep debris from the roof installation, rain or any other contaminants out of the HVAC system, poly plastic sheeting is placed on the curb openings and secured with duct tape. Poly plastic is also commonly duct taped around duct openings in the interior of buildings. This process is cumbersome, time-consuming and often requires two people.